Crude Oil Supply and Inventory Purchase Agreement - Recurring Cash Fee Paid (Details) - Interest expense - J. Aron - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	$ 4.8	$ 7.3	$ 10.0	$ 13.6
El Dorado Refinery
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	2.7	3.2	5.9	5.7
Krotz Spring Refinery
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	1.0	2.6	2.0	5.0
Big Spring refinery
Oil and Gas, Delivery Commitment [Line Items]
Recurring cash fees paid	$ 1.1	$ 1.5	$ 2.1	$ 2.9